Scroll compressor

ABSTRACT

In a scroll compressor, a sliding direction of a Oldham coupling is defined such that an acting direction of an inertia force of the Oldham coupling is substantially opposite to an acting direction of a reaction force by gas compression, and thereby a range of fluctuation of a total torque of a first rotational torque acting on an orbiting scroll by the reaction force of gas compression and a second rotational torque of sliding movement of the Oldham coupling becomes smaller than that of the first rotational torque to suppress a noise and vibration caused by fluctuation of a rotational torque of the orbiting scroll without any limited designing of an involute shape thereof.

TECHNICAL FIELD

The present invention relates to a scroll compressor, and particularlyto a technology of suppressing an operating noise and vibration causedby fluctuation of a rotational torque of an orbiting scroll.

BACKGROUND ART

Conventionally, a scroll compressor has been used as a compressor tocompress a refrigerant in a refrigerating cycle, as disclosed, forexample, in Japanese Laid-Open Patent Publication No. 5-312156. Thescroll compressor includes a compression mechanism with a fixed scrolland an orbiting scroll that have protruding involute wraps engaged witheach other in a casing. The fixed scroll is fixed to the casing by, forexample, a fixing member (hereinafter, referred to as a housing) and theorbiting scroll is coupled to an eccentric shaft portion of a driveshaft. Further, the scroll compressor is constituted such that theorbiting scroll just revolves orbitally to the fixed scroll withoutrotating on its own axis, thereby contracting a compression chamberformed between the wraps of both scrolls to compress the refrigeranttherein.

In the scroll compressor, for example, an Oldham coupling has been usedto enable the above operation of the orbiting scroll. The Oldhamcoupling is provided with two pair of keys, which project at its obverseand reverse faces so as to cross each other at a right angle in adirection perpendicular to an axis of the drive shaft. Further, two pairof key grooves are formed at the outer face of the housing and the backface of the orbiting scroll so as to correspond to the above keys.Engagement of the keys with the key grooves prevents the orbiting scrollfrom rotating on its own axis during the rotation of the derive shaft,while continuous changing of the amount of movement in the direction ofeach key groove enables its orbital revolution around the rotationalaxis of the drive shaft.

A lateral-direction load and an axial-direction load act on the orbitingscroll as a reaction force of the refrigerant due to compressing of therefrigerant. Also, a rotational torque acts on the orbiting scroll dueto the above lateral-direction load. The rotational torque, whichincludes a moment (herein, referred to as a first rotational torque)produced by a lateral-direction element of the refrigerant's reactionforce as its main element, has a function of making the orbiting scrollrotate on its own axis. The first rotational torque increases ordecreases cyclically depending on changing of a refrigerant's pressurein the compression chamber during the orbital revolution of the orbitingscroll, and it becomes the greatest when the orbiting scroll reaches toits revolutionary position where the refrigerant's pressure becomes thegreatest.

Further, the rotational torque of the orbiting scroll changes itsmagnitude depending on moments caused by various factors such as a shapeof wrap, a position of the center of gravity of the orbiting scroll, amanufacturing error between the rotational center and the wrap center, achanging inertia force by the movement of Oldham coupling, and operatingconditions of the compressor (a moment caused by the inertia force ofthe Oldham coupling is referred to as a second rotational torque in thepresent description).

Problem to be Solved

In the meantime, in a so-called symmetric-volute structure having thesame length of a fixed-side wrap as that of an orbiting-side wrap, theabove rotational torque just changes only in its magnitude, having itsunchanging acting direction. Meanwhile, in a so-called asymmetric-volutestructure having a different length of the fixed-side wrap from that ofthe orbiting-side wrap, the rotational torque may not only change in itsmagnitude in a cycle but also reverse its acting direction. The reasonfor this is considered as follows. That is, a reaction force of therefrigerant's pressure in the first compression chamber formed betweenthe wrap-outer peripheral face of the orbiting scroll and the wrap-innerperipheral face of the fixed scroll, and a reaction force of therefrigerant's pressure in the second compression chamber formed betweenthe wrap-inner peripheral face of the orbiting scroll and the wrap-outerperipheral face of the fixed scroll may be basically balanced all thetime during the orbital revolution of the orbiting scroll in thesymmetric-volute structure. In the asymmetric-volute structure, however,there may exist an area where the above reaction forces are imbalanced.

Especially, in particular operating conditions such as a high-speedoperation, the inertia force of the Oldham coupling becomes great, andthereby the direction of the rotational torque acting on the orbitingscroll tends to reverse. Accordingly, there was a problem that keys ofthe Oldham coupling shake in clearances in the key grooves of the hosingand the orbiting scroll, thereby producing a vibration and a noise.

The asymmetric-volute structure shows a tendency that the abovevibration and noise occur more noticeably than the symmetric-volutestructure. However, even the symmetric-volute structure have also a riskthat the vibration of key may occur due to the fluctuation of therotational torque, and therefore a stable operation with less torquevibration should be desirable for the symmetric-volute structure aswell.

In the meantime, it may be possible to improve an involute shape of thewrap by design changing to reduce the rotational torque itself, and itis considered that this design changing may lessen the range offluctuation of the rotational torque and the risk of the key shaking mayreduce. In this case, however, there may be some possibility that designconditions, such as dimension or strength of wrap, or necessarycompression characteristics, are not satisfied to the contrary.Accordingly, in fact it was very difficult to design simply to suppressonly the rotational torque of the orbiting scroll.

The present invention has been devised in view of the above problems,and an object of the present invention is to suppress the noise andvibration caused by the fluctuation of the rotational torque of theorbiting scroll, without any limited designing of the wrap.

DISCLOSURE OF THE INVENTION

The present invention aims at suppressing the fluctuation of totalrotational torque (T) by defining a relationship between a fluctuatingcycle of the inertia force of the Oldham coupling (39), which is one offluctuating factors of the above rotational torque (T), and afluctuating cycle of the gas reaction force, in view of the fact thatthe fluctuation of the above inertia force behaves its action that isindependent from the fluctuation of the gas reaction force.

Specifically, the present invention provides a scroll compressorincluding a fixed scroll (24), an orbiting scroll (26) and an Oldhamcoupling (39) in a casing (10) thereof, the orbiting scroll (26) forminga compression chamber (40) together with the fixed scroll (24), theOldham coupling (39) being capable of sliding in a first direction thatis perpendicular to an axis of a drive shaft (17) to the fixed scroll(24) and capable of sliding in a second direction that is perpendicularto the axis of the drive shaft (17) to the orbiting scroll (26).

Herein, in the scroll compressor defined in claim 1, the first directionis determined so as to provide a phase difference between a firstrotational torque (T1) that acts on the orbiting scroll (26) with cyclicfluctuation by a reaction force of a gas in the compression chamber (40)during an orbital revolution of the orbiting scroll (26) and a secondrotational torque (T2) that acts on the orbiting scroll (26) with cyclicfluctuation by sliding movement of the Oldham coupling (39) in the firstdirection, such that a range of fluctuation of a total torque (T) of thefirst rotational torque (T1) and the second rotational torque (T2)becomes smaller than that of the first rotational torque (T1).

As described above, the rotational torque (T) occurring during theorbital revolution of the orbiting scroll (26) is the total of momentsthat are produced by various factors, including the moment produced by agas force, and it increases or decreases in magnitude cyclically withone cycle that is equivalent to one orbital revolution of the orbitingscroll (26). And, in the present invention defined in claim 1, thereaction force of gas compression and the inertia force of slidingmovement of the Oldham coupling (39) produce an action to make the rangeof fluctuation of the total torque (T) smaller than that of the firstrotational torque (T1) during the orbital revolution of the orbitingscroll (26). Accordingly, this can prevent the orbiting scroll (26) fromrotating on its own axis in the reverse direction during the orbitalrevolution of the orbiting scroll (26). Thus, any vibration of theOldham coupling (39) does not occur easily and the orbital revolution ofthe orbiting scroll (26) is made stable.

Next, the present invention defined in claims 2 or 3 defines a phasedifference between the cyclic fluctuation of the first rotational torque(T1) and the cyclic fluctuation of the second rotational torque (T2) byan angle.

Specifically, according to the present invention defined in claim 2, thefirst direction is determined so as to provide a phase difference of150° to 210° between cyclic fluctuation of a first rotational torque(T1) that acts on the orbiting scroll (26) by a reaction force of a gasin the compression chamber (40) during an orbital revolution of theorbiting scroll (26) and cyclic fluctuation of a second rotationaltorque (T2) by sliding movement of the Oldham coupling (39) in the firstdirection.

Further, according to the present invention defined in claim 3, in thescroll compressor of claim 2, the first direction of sliding movement ofthe Oldham coupling (39) is determined so as to provide a phasedifference of substantial 180° between the cyclic fluctuation of thefirst rotational torque (T1) and the cyclic fluctuation of the secondrotational torque (T2).

According to these present inventions defined by claims 2 and 3, becausethe cyclic fluctuation of the first rotational torque (T1) by the gasreaction force during the orbital revolution of the orbiting scroll (26)and the cyclic fluctuation of the second rotational torque (T2) by thesliding movement of the Oldham coupling (39) have the above phasedifference, an offsetting function by the first rotational torque (T1)and the second rotational torque (T2) occurs. Accordingly, the range offluctuation of the total torque (T) can be made smaller than that of thefirst rotational torque (T1) by the gas reaction force. Thus, this canprevent the orbiting scroll (26) from rotating on its own axis in thereverse direction during the orbital revolution of the orbiting scroll(26), and thereby any vibration of the Oldham coupling (39) does notoccur easily and the orbital revolution of the orbiting scroll (26) ismade stable.

Next, the scroll compressor defined in claims 4 or 5 defines the slidingdirection of the Oldham coupling (39) based on a certain position(position where the gas reaction force becomes the greatest) of theorbital revolution of the orbiting scroll (26).

Specifically, according to the present invention defined in claim 4, thefirst direction is determined so as to cross a straight line that passesthrough the centers (01,02) of the both scrolls (24,26) at an angle of60° to 120° on a plane perpendicular to the axis of the drive shaft (17)when the orbiting scroll (26) reaches to its revolutionary positionwhere a reaction force of a gas in the compression chamber (40) duringan orbital revolution of the orbiting scroll (26) becomes the greatest.

Further, according to the present invention defined in claim 5, in thescroll compressor of claim 4, the first direction of sliding movement ofthe Oldham coupling (39) is determined so as to cross the straight linethat passes through the centers (01,02) of the both scrolls (24,26) atan angle of substantial 90° on the plane perpendicular to the axis ofthe drive shaft (17) when the orbiting scroll (26) reaches to itsrevolutionary position where the reaction force of the gas in thecompression chamber (40) during the orbital revolution of the orbitingscroll (26) becomes the greatest.

It can be said that the first rotational torque (T1) by the reactionforce of gas compression, as described above, becomes the greatest whenthe gas pressure in the compression chamber (40) is the greatest, andthe lateral-direction element of the gas reaction force acts in acertain direction that is substantially perpendicular to the linepassing through the center (02) of the orbiting scroll (26) at this timeand the center (01) of the fixed scroll (24). Accordingly, according tothe present inventions of claims 4 and 5, it is possible to make thesliding direction of the Oldham coupling (39) substantially reverse tothe acting direction of gas reaction force at the above revolutionaryangle, and thereby a situation can be made where the gas reaction forceis offset substantially by the inertia force of the Oldham coupling(39). Thus, the range of fluctuation of the total rotational torque (T)is made smaller than that of the first rotational torque (T1) by the gasreaction force, and the orbiting scroll (26) can be prevented fromrotating on its own axis in the reverse direction during the orbitalrevolution of the orbiting scroll (26). As a result, any vibration ofthe Oldham coupling (39) does not occur easily and the orbitalrevolution of the orbiting scroll (26) is made stable.

Further, according to the present invention defined in claim 6, in thescroll compressor of any one of the preceding claims, the fixed scroll(24) and the orbiting scroll (26) are constituted in asymmetric-volutestructure having different length of volutes.

In general, the asymmetric-volute structure makes the range offluctuation of the rotational torque (T) great due to imbalance of gasreaction force during the revolution, and thereby the Oldham coupling(39) tends to generate vibration easily. However, in the presentinvention defined in claim 6, as described as to the inventions ofclaims 1 through 5, the gas reaction force and the inertia force of theOldham coupling (39) function so as to make the range of fluctuation ofthe rotational torque (T) small. Therefore, it is possible to prevent anoccurring direction of the rotational torque (T) from reversing.Accordingly, even though it has the volute structure that tends togenerate vibration easily, the vibration can be suppressed certainly.

Effect

According to the present invention defined in claim 1, because thesliding direction of the Oldham coupling (39) is determined so as togenerate the function that the range of fluctuation of the total torque(T) by the reaction force of gas compression and the inertia force ofsliding movement of the Oldham coupling (39) becomes smaller than thatof the first rotational torque (T1) by gas compression, the orbitingscroll (26) can be prevented from rotating on its own axis in thereverse direction during the orbital revolution of the orbiting scroll(26). Thus, any vibration of the Oldham coupling (39) and any noisecaused by this vibration do not occur easily, and the stable operationwith less torque fluctuation can be obtained. Further, because there isno need to change the volute shape of the orbiting scroll (26) in thisstructure to suppress fluctuation of the rotational torque (T), anydesigning limitation of the compressing mechanism by the determinationof the sliding direction of the Oldham coupling (39) can be also avoidedwithout any deterioration of the desired function.

Further, according to the present invention defined in claim 2, becausethe sliding direction (first direction) of the Oldham coupling (39) isdetermined so as to provide the phase difference of 150° to 210° betweenthe cyclic fluctuation of the first rotational torque (T1) and thecyclic fluctuation of the second rotational torque (T2), it is possibleto make the range of fluctuation of the total rotational torque (T)smaller than that of the first rotational torque (T1) and thereby thevibration and noise can be prevented.

Further, according to the present invention defined in claim 3, becausethe above angle is determined at substantial 180° such that cyclicfluctuation of the both torques are differed by ½ cycle from each other,the effect of claim 2 can be furthered.

Further, according to the present invention defined in claim 4, becausethe first direction in which the Oldham coupling slides is determined soas to cross the straight line passing through the centers (01,02) of thefixed scroll (24) and the orbiting scroll (26) at the angle of 60° to120° on the plane perpendicular to the axis when the orbiting scroll(26) reaches to its revolutionary position where the reaction force ofthe gas in the compression chamber (40) during the orbital revolution ofthe orbiting scroll (26) becomes the greatest, it is possible, like theinvention defined in claim 2, to make the range of fluctuation of thetotal rotational torque (T) smaller than that of the first rotationaltorque (T1) and thereby the vibration and noise can be prevented.

Further, according to the present invention defined in claim 5, becausethe above angle is set at substantial 90°, the cyclic fluctuation of theboth torques (T1, T2) are differed by ½ cycle from each other like theinvention of claim 3, and the range of fluctuation of the totalrotational torque (T) can be suppressed certainly and thereby the effectof claim 4 can be furthered.

Further, according to the present invention defined in claim 6, therange of fluctuation of the rotational torque (T) can be suppressedcertainly in the asymmetric-volute structure in which the range offluctuation of the rotation torque (T) tends to become great, and theoccurring direction of the rotational torque (T) can be prevented fromreversing. Further, the vibration and noise caused by the fluctuation ofthe rotational torque (T) of the scroll compressor having theasymmetric-volute structure can be suppressed certainly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial sectional view of a scroll compressor according toan embodiment of the present invention.

FIG. 2 is a sectional view for showing an essential part of an orbitingscroll that is located at a position where a refrigerant's reactionforce in a compression chamber becomes the greatest.

FIG. 3 is an enlarged sectional view for showing around a housing-sidekey of an Oldham coupling.

FIG. 4 is a perspective view of the Oldham coupling.

FIG. 5 is a perspective view of the orbiting scroll.

FIG. 6 is an explanatory diagram for showing a state where a rotationaltorque of the orbiting scroll occurs.

FIG. 7 is a sectional view for showing an essential part of a scrollcompressor according to a comparative sample.

FIG. 8 is a graph for showing a state in which load acting on each keyof the Oldham coupling fluctuates according to a revolutionary position.

FIG. 9 is a graph for showing a state in which load denoted by F2 inFIG. 8 fluctuates according to a rotational speed.

FIG. 10 is a graph for showing a state in which a minimum value of theload acting on each key of the Oldham coupling in the present embodimentfluctuates according to a sliding direction of the Oldham coupling.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described in detail withreference to the accompanying drawings. FIG. 1 shows a scroll compressor(1) according to the present embodiment. The scroll compressor (1) isconnected to a refrigerating circuit, not shown in any drawing, whichperforms a vapor-compression type of refrigerating-cycle operation witha refrigerant circulated therein.

The scroll compressor (I) includes a sealed dome-type casing (10) with alongitudinal-cylinder shape. In the casing (10), a scroll compressingmechanism (15) to compress the refrigerant and a driving motor (notshown in any drawing) disposed below the scroll compressing mechanism(15) are installed. The scroll compressing mechanism (15) and thedriving motor are coupled by a drive shaft (17) that is disposed in thecasing (10) so as to extend in the vertical direction. Between thescroll compressing mechanism (15) and the driving motor, a high-pressurespace (18) filled with a compressed gas refrigerant is provided.

The scroll compressing mechanism (15) includes a housing (23), a fixedscroll (24) and an orbiting scroll (26). The housing (23) is a fixingmember to fix the compressing mechanism (15) to the casing (10), whichis fixed to the casing (10) by pressure inserting at its entireouter-peripheral surface. The fixed scroll (24) is fixed to an upperface of the housing (23) so as to contact thereto. The orbiting scroll(26) is disposed between the fixed scroll (24) and the housing (23),which is constituted so as to be movable to the fixed scroll (24).

The housing (23) is provided with a housing recess (31) formed at thecenter of an upper face thereof, and a radial bearing portion (32)extending downwardly from the center of a lower face thereof. A pair ofkey grooves (23 a, 23 a), which will be described later, are formed atthe housing (23). A radial bearing hole (33) that penetrates from thelower-end face of the above radial bearing portion (32) to the bottomface of the housing recess (31) is also formed at the housing (23), bywhich the drive shaft (17) is supported through a sliding bearing (34)so as to rotate freely therein.

The above casing (10) is closed by an upper end plate (10 a) at itsupper-end portion. A suction pipe (19) to introduce the refrigerant inthe refrigerating circuit into the scroll compressing mechanism (15) isconnected to the upper end plate (10 a) of the casing (10). Also, adischarge pipe (20) to discharge the high-pressure refrigerant in thecasing (10) out of the casing (10) is connected to the center portion inthe vertical direction of the casing (10). An inner-end portion of thesuction pipe (19) is connected through the fixed scroll (24) to acompression chamber (40) that will be described later. The refrigerantis sucked into the compression chamber (40) from the suction pipe (19).

The fixed scroll (24) is comprised of an end plate (24 a) and aninvolute wrap (24 b) formed at a lower face of the end plate (24 a).Meanwhile, the orbiting scroll (26) is comprised of an end plate (26 a)and an involute wrap (26 b) formed at an upper face of the end plate (26a). The wrap (24 b) of the fixed scroll (24) and the wrap (26 b) of theorbiting scroll (26) are engaged with each other. Further, thecompression chamber (40) is formed between contacting portions of theboth wraps (24 b, 26 b) of the fixed scroll (24) and the orbiting scroll(26).

The compression chamber (40), as shown in FIG. 2, is comprised of anouter-periphery-side compression chamber (40 a), which is formed betweenan inner peripheral face of the wrap (24 b) of the fixed scroll (24) andan outer peripheral face of the wrap (26 b) of the orbiting scroll (26),and an inner-periphery-side compression chamber (40 b), which is formedbetween an outer peripheral face of the wrap (24 b) of the fixed scroll(24) and an inner peripheral face of the wrap (26 b) of the orbitingscroll (26). In the present embodiment, the compressing mechanism (15)has an asymmetric-volute structure in which the length of the wrap (24b) of the fixed scroll (24) is different from that of the wrap (26 b) ofthe orbiting scroll (26), and the outer-periphery-side compressionchamber (40 a) and the inner-periphery-side compression chamber (40 b)are disposed asymmetrically against the center (01) of the fixed scroll(24).

As shown in FIG. 1, the orbiting scroll (26) is supported at the housing(23) through an Oldham coupling (39). The Oldham coupling (39) is aring-shape member that is made from, for example, aluminum, and it isconstituted such that a pair of orbiting-scroll-side keys (39 a, 39 a)and a pair of housing-side keys (39 b,39 b) project respectively, asshown in FIG. 4. The orbiting-scroll-side keys (39 a,39 a) are formed atthe obverse side of the Oldham coupling (39), while the housing-sidekeys (39 b,39 b) are formed at the reverse side of the Oldham coupling(39) so as to be located at a position which has a 90° different phasefrom the orbiting-scroll-side keys (39 a,39 a) to an axial center of thedrive shaft (17).

Meanwhile, as shown in FIG. 5, key grooves (26 c,26 c) are formed at theback of the orbiting scroll (26), corresponding to theorbiting-scroll-side keys (39 a,39 a). Further, as shown in the enlargedview of FIG. 3, key grooves (23 a, 23 a) are formed at the obverse ofthe housing (23), corresponding to the housing-side keys (39 b, 39 b).Then, two pair of key grooves (26 c,23 a) and the keys (39 a,39 b) areengaged with each other so as to constitute the Oldham coupling (39)that is capable of sliding in the first direction (lateral direction inFIG. 2), which is perpendicular to the axial center (rotational center)of the drive shaft (17), to the fixed scroll (24), and capable ofsliding in the second direction (vertical direction in FIG. 2), which isperpendicular to the above axial center, to the orbiting scroll (26).

As shown in FIG. 1, a cylindrical boss (26 d) is formed so as to projectat the center of a lower face of the end plate (26 a) of the orbitingscroll (26). Meanwhile, the drive shaft (17) is provided with aneccentric-shaft portion (17 a) at its upper end. The eccentric-shaftportion (17 a) is inserted in the boss (26 d) of the orbiting scroll(26) through a sliding bearing (27) so as to rotate freely. Further, thedrive shaft (17) is provided with a counter weight (not shown in anydrawing) at a lower-side portion of the radial bearing portion (32) ofthe housing (23) to keep a dynamic balance with the orbiting scroll(26), the eccentric-shaft portion (17 a) and the like. The drive shaft(17) rotates balancing weight by the counter weight.

With the rotation of the drive shaft (17), the Oldham coupling (39)slides reciprocatingly in the first direction to the fixed scroll (24)along the key grooves (23 a,23 a) at the side of housing (23), and theorbiting scroll (26) slides reciprocatingly in the second direction tothe Oldham coupling (39) along the key grooves (26 c,26 c). As a result,the orbiting scroll (26) just revolves orbitally to the fixed scroll(24) without rotating on its own axis. At this time, the compressionchamber (40) between the both wraps (24 b, 26 b) contracts toward thecenter thereof with the revolution of the orbiting scroll (26), therebycompressing the refrigerant sucked through the suction pipe (19).

Meanwhile, the scroll compressor (15) is provided with a gas passage(not shown in any drawing) that is formed over the fixed scroll (24) andthe housing (23) so as to connect the compression chamber (40) and thehigh-pressure space (18). Accordingly, the high-pressure refrigerantcompressed in the compression chamber (40) is discharged from adischarge hole (41) that is formed at an end portion of the above gaspassage (see FIG. 2) to the high-pressure space (18) through the gaspassage, and then flows out of the discharge pipe (20) into therefrigerating circuit.

In the involute shape of the wraps (24 b,26 b) according to the presentembodiment, a revolutionary position of the orbiting scroll (26) wherethe pressure of the refrigerant in the compression chamber (40) becomesthe greatest (this revolutionary position corresponds substantially to arevolutionary position where a first rotational torque (T1) by areaction force of the refrigerant becomes the greatest) is located atabout 90° (at the upper side of the center (01) of the fixed scroll(24)) as shown in FIG. 2, assuming that the revolutionary position is astandard (0°) when the center (02) of the orbiting scroll (26) islocated at the right side of the center (01) of the fixed scroll (24) inFIG. 2.

The key grooves (23 a, 23 a) at the side of the housing (23) are formedat positions of 0° and 180°, respectively. Also, the key grooves (26c,26 c) at the side of the orbiting scroll are formed at positions thatare perpendicular to the key grooves (23 a,23 a) at the side of thehousing (23), seeing from the center-line direction of the drive shaft(17), namely at positions of 90° and 270° in the drawing.

The Oldham coupling (39) executes a reciprocating sliding-movement tothe fixed scroll (24) along the key grooves (23 a, 23 a) at the side ofthe housing (23). Accordingly, the sliding direction (first direction)of the Oldham coupling (39) crosses the straight line that passesthrough the centers (01, 02) of the both scrolls (24, 26) at a stateshown in FIG. 2 where the first rotational torque (T1) becomes almostthe greatest, at an angle of substantial 90° on a plane that isperpendicular to the axis of the drive shaft (17). An inertia force (F0)of the Oldham coupling (39) becomes the greatest at its middle positionof the reciprocating sliding-movement. Accordingly, in the abovepositional relationship, when the revolutionary position of the orbitingscroll (26) is at positions of 90° and 270°, the absolute value of theinertia force (F0) becomes the greatest.

Next, an operation state of the scroll compressor (1) according to thepresent embodiment will be described. The drive shaft (17) rotates withstarting of the driving motor, and its driving power is conveyed to theorbiting scroll (26) of the scroll compressing mechanism (15). At thistime, the eccentric-shaft portion (17 a) of the drive shaft (17)revolves on a certain revolutionary orbit, while the Oldham coupling(39) slides in the first direction to the fixed scroll (24) by thefunction of the key (39 b) and the key groove (23 a) and the orbitingscroll (26) slides in the second direction to the Oldham coupling (39)by the function of the key (39 a) and the key groove (26 c), andtherefore the orbiting scroll (26) revolves orbitally without rotatingon its own axis.

Thereby, a low-pressure gas refrigerant that has been evaporated at anevaporator in the refrigerating circuit not shown in any drawing issucked into the compression chamber (40) from the peripheral-edge sideof the compression chamber (40) through the suction pipe (19). Therefrigerant is compressed and increases in pressure with changing of thedisplacement of the compression chamber (40) in the scroll compressingmechanism (15), and then it flows into the high-pressure space (18)through the discharge hole (41) and the gas passage. When discharged outof the casing (10) from the discharge pipe (20), the refrigerantcirculates in the refrigerating circuit and then is sucked again intothe scroll compressor (1) through the suction pipe (19). This operationis repeated in the present embodiment.

Meanwhile, during the orbital revolution of the orbiting scroll (26), arefrigerant's reaction force that may enlarge the outer-periphery-sidecompression chamber (40 a) and the inner-periphery-side compressionchamber (40 b) due to the refrigerant compressed in the compressionchamber (40) acts on the orbiting scroll (26).

The above refrigerant's reaction force is comprised of alateral-direction load and an axial-direction load. The function of thelateral-direction load (FT) is shown in FIG. 6 in simplified way.Assuming that the lateral-direction load (FT) acts on one point(hereinafter, referred to as acting point (P1)) on the straight lineconnecting the center (02) of the orbiting scroll (26) with the center(01) of the fixed scroll (24) as shown in this figure, the firstrotational torque (T1) by the refrigerant's reaction force is determinedby multiplying the lateral-direction load (FT) by the distance betweenthe center (01) of the fixed scroll (24) and the acting point (PI). Thefirst rotational torque (T1) becomes the greatest at the revolutionaryposition where the reaction force of the refrigerant compressed in thecompression chamber (40) during the orbital revolution of the orbitingscroll (24) becomes the greatest, and at this time the lateral-directionload (FT) acts in the direction that is substantially perpendicular tothe straight line passing through the centers (01, 02) of the fixedscroll (24) and the orbiting scroll (26).

Meanwhile, the rotational torque (T) of the orbiting scroll (26), asdescribed above, is the sum of the first rotational torque (T1) by therefrigerant's reaction force and moments by other aspects. In thepresent embodiment, defining the sliding direction (first direction) ofthe Oldham coupling (39), which is one of factors for the fluctuation,as described above makes the inertia force (F0) act in the oppositedirection to the lateral-direction load (FT) by the refrigerant'sreaction force, result in suppressing a fluctuation of the total torque(T).

Specifically, when the revolutionary position of the orbiting scroll(26) is located at the position of 90° in FIGS. 2 and 6, thelateral-direction element (FT) by the refrigerant's reaction force withits greatest value acts on the orbiting scroll (26) in the rightdirection in FIG. 6, while the Oldham coupling (39) is under movement inthe left direction in the figure along the key grooves (23 a,23 a) atthe side of the housing (23) with the orbital revolution of the orbitingscroll (26) and the inertia force (F0) becomes the greatest at thistime. Accordingly, because the refrigerant's reaction force (FT) and theinertia force (F0) act in the opposite directions to each other withtheir greatest value, they act so as to offset each other and therebythe maximum value of the total rotational torque (T) acting on theorbiting scroll (26) becomes small.

According to this, the phase difference between the cyclic fluctuationof the first rotational torque (T1) by the gas reaction force and thecyclic fluctuation of the second rotational torque (T2) by the slidingmovement of the Oldham coupling (39) becomes substantial 180° as shownlater. Thus, the range of fluctuation of the total torque (T) of thefirst rotational torque (T1) and the second rotational torque (T2) iscontracted so as to be smaller than that of the first rotational torque(T1).

Accordingly, the total rotational torque (T) acting on the orbitingscroll (26) is made stable, any force to turn the orbiting scroll (26)reversely does not occur easily, and any shaking between the keys (39a,39 b) of the Oldham coupling (39) and the key grooves (26 c,23 a) ofthe orbiting scroll and the housing does not occur easily either. Thus,it is possible to prevent the noise and the vibration of the scrollcompressor (1) from occurring.

Herein, the present embodiment is constituted such that the lineconnecting the center (02) of the orbiting scroll (26) with the center(01) of the fixed scroll (24) when the refrigerant's reaction forcebecomes the greatest crosses the first direction of sliding of theOldham coupling (39) at an angle of 90°. However, the crossing angle maybe changed in the present invention, as long as the range of fluctuationof the total rotational torque (T) becomes smaller than that of thefirst rotational torque (T1).

Next, the first direction in which the Oldham coupling (39) slides tothe fixed scroll (24) will be described in detail with a comparativesample.

In the comparative sample, the positional angle of the two pair of keys(39 a, 39 b) and the key grooves (26 c, 23 a) are different from that ofthe above embodiment by 90°. Namely, in the comparative sample, as shownin FIG. 7, the key grooves (26 c, 26 c) of the orbiting scroll (26) arelocated at the positions which are equivalent to the revolutionaryposition of the orbiting scroll (26) of 0° and 180°, while the keygrooves (23 a, 23 a) at the side of the housing (23) are located at thepositions equivalent to that of 90° and 270°. In this structure, theorbiting scroll (26) is constituted such that the direction of the lineconnecting the center (02) of the orbiting scroll (26) with the center(01) of the fixed scroll (24) when the first rotational torque (T1) bythe refrigerant's compression becomes the greatest corresponds to thefirst direction of sliding of the Oldham coupling (39) (slidingdirection to the fixed scroll (24)).

In this structure, load characteristics by the inertia force acting onrespective keys (39 a,39 a) of the Oldham coupling (39) with theorbiting scroll (26) rotated at a speed of 60 revolutions per second wasinvestigated. In FIG. 8, loads (F1-F4) show the loads occurring onrespective orbiting-scroll-side keys (39 a,39 a) at 0°, 180° andrespective housing-side keys (39 b,39 b) at 90° and 270°, in order.These loads (F1-F4) having their negative values have a risk to reversethe rotational torque (T). The load (F2) acting on theorbiting-scroll-side key (39 a) at the position of 180° in the aboveloads (F1-F4) is the one having the smallest value thereof, which isconsidered to have a high risk to reverse the rotational torque (T).Herein, the load (F2) will be examined.

Firstly, the load (F2) acting on the orbiting-scroll-side key (39 a) atthe position of 180° was examined by changing the speed of the orbitingscroll (26) from 60 to 100 revolutions per second. FIG. 9 shows results.As shown in this figure, a state can be understood where the range offluctuation of the load (F2) enlarged with the speed increasing and theload (F2) turned to a negative value at the revolutionary position ofthe orbiting scroll (26) of 270° especially after the speed exceeded 90revolutions per second. Accordingly, there arises a high risk at thispoint that the acting direction of the rotational torque (T) reverses.Once reversing of the rotational torque (T) arises, the keys (39 a,39 b)of the Oldham coupling (39) hit one time at the key grooves (23 a,26 c)during one orbital revolution of the orbiting scroll (26), therebycausing noise and vibration of the scroll compressor (1).

Now, a disposition angle (θ) of the keys (39 a, 39 b) the Oldhamcoupling (39) that is appropriate to suppress the above vibration willbe examined. Firstly, setting the deposition angle (θ) of the keys (39a, 39 b) of the comparative sample at the standard (0°), eachfluctuation of the loads (F1-F4) was analyzed by changing thedisposition angle in the range of from 0° to 180°. FIG. 10 showsresults.

As shown in FIG. 10, the load (F1) became negative values in the rangeof the disposition angle (θ) that is greater than 120°, while the load(F2) became negative values in the range of the disposition angle (θ)that is smaller than 60°. Accordingly, it can be considered that in arange excluding the above angles (range between 60° and 120°) the totaltorque (T) may not reverse and thereby the noise and vibration of thescroll compressor (1) can be suppressed because the loads have alwaystheir positive values therein. In other words, it can be understood thatthe disposition angle (θ) of the keys (39 a,39 b) should be setappropriately in a range that is 30° above and below the dispositionangle of the above embodiment.

Accordingly, it can be understood that the first direction of sliding ofthe Oldham coupling (39) should be set appropriately so as to cross thestraight line that passes through the centers (01,02) of the fixedscroll (24) and the orbiting scroll (26) at the revolutionary positionwhere the reaction force of the gas compressed in the compressionchamber (40) between the both scrolls (24,26) becomes the greatestduring the orbital revolution of the orbiting scroll (26), at an anglewithin 60° to 120° on the plane which is perpendicular to the rotationalaxial center of the drive shaft (17). Namely, it is the best to set thefirst direction at the position of 90° to the above straight line(position where the phase difference between respective fluctuation ofthe first rotational torque (T1) and the second rotational torque (T2)becomes 180°), and it is appropriate to set in a range that is 30° aboveand below the above position.

According to this, the phase difference between the cyclic fluctuationof the first rotational torque (T1) acting on the orbiting scroll (26)by the reaction force of the gas compressed in the compression chamber(40) during the orbital revolution of the orbiting scroll (26) and thecyclic fluctuation of the second rotational torque (T2) by the slidingmovement in the first direction of the Oldham coupling (39) becomesabout a half of cycle (180°±30°). Accordingly, the first rotationaltorque (T1) and the second rotational torque (T2) act so as to offsetthe fluctuation range of each other, and thereby reversing of the totalrotational torque (T) can be prevented and the noise and vibration ofthe scroll compressor (1) can be suppressed.

Industrial Applicability

As described above, the present invention is useful for the scrollcompressor.

1. A scroll compressor comprising: a casing having a fixed scroll, anorbiting scroll and an Oldham coupling therein, said orbiting scrollforming a compression chamber together with said fixed scroll saidOldham coupling being configured to slide in a first direction that isperpendicular to an axis of a drive shaft to the said fixed scroll andsliding being configured to slide in a second direction that isperpendicular to said axis of said drive shaft to said orbiting scroll:said first direction being determined so as to provide a phasedifference between a first rotational torque acting on said orbitingscroll with cyclic fluctuation by a reaction force of a gas in saidcompression chamber during an orbital revolution of said orbiting scrolland a second rotational torque on said orbiting scroll with cyclicfluctuation by sliding movement of said Oldham coupling in said firstdirection, such that a range of fluctuation of a total torque of saidfirst rotational torque and the said second rotational torque becomingsmaller than that of said first rotational torque.
 2. A scrollcompressor including comprising: a casing having a fixed scroll, anorbiting scroll and an Oldham coupling therein, said orbiting scrollforming a compression chamber together with said fixed scroll, saidOldham coupling being configured to slide in a first direction that isperpendicular to an axis of a drive shaft to said fixed scroll and beingconfigured to slide in a second direction that is perpendicular to saidaxis of said drive shaft to said orbiting scroll: said first directionbeing determined so as to provide a phase difference of 150° to 210°between a cyclic fluctuation of a first rotational torque acting on saidorbiting scroll by a reaction force of a gas in said compression chamberduring an orbital revolution of said orbiting scroll and a cyclicfluctuation of a second rotational torque by sliding movement of saidOldham coupling in said first direction.
 3. The scroll compressor ofclaim 2, wherein said first direction is determined so as to providesaid phase difference at substantially 180° between said cyclicfluctuation of said first rotational torque and said cyclic fluctuationof said second rotational torque.
 4. A scroll compressor comprising: acasing having a fixed scroll, an orbiting scroll and an Oldham couplingtherein, said orbiting scroll forming a compression chamber togetherwith said fixed scroll, said Oldham coupling being configured to slidein a first direction that is perpendicular to an axis of a drive shaftto said fixed scroll and being configured to slide in a second directionthat is perpendicular to said axis of the said drive shaft to saidorbiting scroll: said first direction being determined so as to cross astraight line passing through the centers of said fixed and orbitingscrolls at an angle of 60° to 120° on a plane perpendicular to said axisof said drive shaft when said orbiting scroll reaching a revolutionaryposition where a reaction force of a gas in said compression chamberduring an orbital revolution of said orbiting scroll becoming greatest.5. The scroll compressor of claim 4, wherein said first directiondetermined so as to cross said straight line at an angle ofsubstantially 90° on said plane perpendicular to said axis of said driveshaft when said orbiting scroll reaches said revolutionary position 6.The scroll compressor of claim 1, wherein said fixed scroll and saidorbiting scroll are constituted in a asymmetric-volute structure havingdifferent length volutes.
 7. The scroll compressor of claim 2, whereinsaid fixed scroll and said orbiting scroll are constituted in aasymmetric-volute structure having different length volutes.
 8. Thescroll compressor of claim 3, wherein said fixed scroll and saidorbiting scroll are constituted in a asymmetric-volute structure havingdifferent length volutes.
 9. The scroll compressor of claim 4, whereinsaid fixed scroll and said orbiting scroll are constituted in aasymmetric-volute structure having different length volutes.
 10. Thescroll compressor of claim 5, wherein said fixed scroll and saidorbiting scroll are constituted in a asymmetric-volute structure havingdifferent length volutes.